Abortive infection of Escherichia coli strain W by T2 bacteriophage

Abstract

This paper describes the abortive infection of Escherichia coli strain W by phage T2 and attempts to relate the biology of the infection with the extent of viral synthesis and the fate of the parental DNA. When strain W cells were infected with T2, less than 1% of the cells produced phage; the phage produced were not modified, and only one out of two to three phage were effective killers of strain W. The infection was characterized by an abrupt, early cessation of all macromolecular syntheses. Early phage enzymes were produced at lower than normal levels. No DNA and no late proteins were synthesized. Isotope incorporation data indicated that protein synthesis stopped abruptly early after infection. RNA synthesis continued a few minutes longer than protein synthesis and then stopped. When the fate of 32P-labeled infecting phage DNA was studied, two degradative processes were found. Initially there was a rapid degradation of 30 to 50% of the phage DNA molecules to acid-soluble fragments. When this activity was completed, the remaining acid-precipitable phage DNA was intact as measured by neutral and alkaline sucrose gradient centrifugation, thus indicating that the prior acid solubilization did not involve these molecules. The remaining intact DNA was subsequently slowly attacked by a double-stranded endonuclease which cleaved the DNA to smaller acid-precipitable pieces. It is postulated that these nucleolytic activities are related to the reduced efficiency of killing strain W by T2 infection, although they may not be the primary cause of the inability to produce phage.